The present invention generally relates to methods and apparatuses for generating characters, and more particularly to a method and apparatus for generating a multi-level character.
Conventionally, a font, that is, a set of characters having the same size and style of penmanship, is generated in two levels of tone. Hence, in the case of a dot printer, for example, each character of the font is printed in black and white where the black shows the shape (or letterform) of the character.
A Japanese Published Patent Application No. 53-41017 shows an example of a conventional system of generating the font. According to this system, an information on an outline (a contour) of each high quality character is stored according to a stroke method. When outputting the stored information, the information is first converted into a dot display signal for dot display and this dot display signal is further converted so that values of each dot signal between two dot signals respectively having a value "1" along a line is converted into a dot signal having a value "1". FIG. 1 shows an example of a character generated by this system, where an arrow denotes a stroke and a hatching denotes a region in which the dot signals all have the value "1". When this character shown in FIG. 1 is printed on the dot printer, for example, the region indicated by the hatching becomes black and the remaining unhatched region becomes white or the color of the paper used.
The above described system is advantageous in that a font of a reasonable quality is obtainable by storing a small quantity of information on each character of the font and that the font can be enlarged or reduced with ease. However, there is a limit to increasing the quality of the font when the font is simply described in two levels of tone which are black and white. Even when the resolution of the printer increases, the printing of a character in two levels of tone cannot produce a character which has additional improved features such as (i) gentle to the human eye, (ii) reduced rigidness of the character and (iii) improved beauty. Therefore, especially in fields in which a relatively large character needs to be finely generated such as laser printer and plotter, a high-resolution cathode ray tube (CRT) and a photographic plate making apparatus, there is a demand to realize a font which has the additional improved features (i) through (iii) described above.